PSEUDODIFFLUGIA AECHERI. 121 



Length 55-110 ju, (Penard gives 50-170 ju, as the 

 limits of length and 80-100 fi as the usual size). 



Habitat. — Deep lakes and aquatic vegetation. 



England. — Shrewsbury, Shropshire ; Devonshire ; 

 Cornwall. 



Wales. — Bodelwyddan, Flintshire. 

 Ireland. — Clare Island and Roonah, Mayo. 



The test is characterized by its thick covering of 

 amorphous silicious particles arranged like a mosaic in 

 the cementing medium, each small particle being 

 isolated from its neighbours. 







Fig. 154 — Fseudodifflugia archeri. x 200. 



The crystals found in the plasma are considered by 

 Penard to consist of some organic compound ; owing 

 to the opacity of the test the contents are not visible 

 vmless the specimen is immersed in oil of cloves or 

 Canada balsam. The plasma and contractile vesicles, 

 etc., cannot be studied in the living animal unless they 

 happen to be protruded from the aperture. 



5. Fseudodifflugia compressa (Schulze) Penard. 

 (Plate LII, figs. 9-11.) - 



Pleurophrys compressa 



Schulze in Aroli. mikr. Anat. XI (1876), p. 125, pi. vii, fE. 4, 5. 

 Archee in Qrt. Jrn. Micr. Sci. (n. s.) YII, p. 204, pi. xiii, ff. 9a, 9b ; 



in Proo. Dubl. Micr. Olub, III, 3 (1880), pp. 273-274, pl.x, if. 9a, 96. 

 Fseudodifflugia compressa 



Penabd Panne Rhiz. Leman (1902), pp. 458-459, 2 figs. ; Sarcodines 



in Cat. Invei'.t. Suisse (1905), p. 93. 

 AvEEiNTZEFP Iq Ti'udui S.-Peterb. Obslich. XXXVI, ll (1906), 



p. 275. 

 ScHoriEDEN in Ann. Biol, lacustre, I (1906), pp. 363, 364. 

 Wailes & Penaed in Proc. R. Irish. Acad. XXXI, Lxv (1911), 



p. 19. 



